Material for polishing, cleaning, or the like and method of making the same



Sept 23, 1941.

L. F. ROWE EI'AL 2,256,528 MATERIAL FOR POLISHING, CLEANING, OR THE LIKEAND METHOD OF MAKING THE SAME Filed May 1, 1939 Java/s yam/v39 sgs'vs oNI aumvaadwn fizvenlaws.

TIME IN MINUTES LOU/S E ROWE ALEX/5 G. P/NCUS CARL G. SILVEEBERG vl-lorrbey.

Patented Sept. 23, 1941 MATERIAL FOR POLISHING, CLEANING, OR I THE LIKEAND METHOD OF MAKING THE SAME Louis F. Rowe, Southbridge, nd Carl G.Silverberg, Brookfield, Mass., an I Alexis G. Pincus, assignors toAmerican Optical Company, Southbridge, Mass., a voluntary association ofMassachusetts Application May 1, 1939, Serial No. 271,210

State College, Pa,

8Claims.

This invention relates to the provision of novel materials forpolishing, cleaning or the like and process of making the same.

One of the principal objects of the invention is to provide a fine grainmaterial with a relatively large available'surface for mechanical andchemical uses and process of making the same.

Another important object of the invention is to provide a non-toxic andnon-pigmenting polishing material and process of making the same.

Another important object'of the invention is to provide a composition ofmatter which is a substitute for commercially known rouge (iron oxide)which has been the almost universal polishing medium, particularly forglass polish-.

ings; which does not stain or discolor objects with which it comes incontact; such as skin, clothing, furniture, buildings, floors, etc.;which does not constitute a health hazard; which is relatively low incost; and which imparts a polish of high quality within a reasonabletime, and which is generally acceptable for commercial use as regardsthe texture of the polished surface.

Another important object is to produce a fine grain material applicableas a polishing material, in addition to many other uses, resulting fromclay calcined to an appropriate temperature and thereafter reducing saidcalcined clay to a proper condition by suitable milling or the like and,in some instances, further treating said clay by a leaching ordissolving out process to remove undesirable soluble materials whichmight have injurious effects upon the polishing efiiciency of the clayor other uses thereof.

Another object is to provide a novel method of treatment of naturalclays to render them effective as polishing means or for other desirableuses by heating the said clays to temperatures above the range in whichthe water of constitution is evolved but below the range which leads toa material which objectionably scratches the surfaces which are to betreated by said clay product.

Other objects and advantages of the invention should become apparentfrom the following description taken in connection with the accompanyingdrawing and it will be apparent that many changes may be made in thearrangements and methods shown and described without de- "parting fromthe spirit of the invention as expressed in the accompanying claims. It,therefore, is to be understood that the invention is not limited to thespecific arrangements and methods shown and described, as the preferredforms only have been given by way of illustration.

Referring to the drawing:

The figure of the drawing shows a typical timetemperature diagram givingthe corresponding temperatures of the material and of the furnace asheating progresses for a specified preferred material embodying theinvention and indicating the temperature ranges in which variousconversions take place for the given material and indicating the'maximumtemperature of heating preferred in this invention.

Considering said materials as polishing means, it has beenusual in thepast, in forming highly polished surfaces on glass or the like, to usean iron oxide known commercially as rouge. Although this rouge ispractical, as regards its polishing characteristics, it has a decidedlyundesirable staining nature, particularly as regards the clothing of theoperator using such rouge, and the machinery, floors, ceilings or otherparts of the building in which such polishing operations are carried on.

Many attempts have been made to overcome the disadvantages of rouge andyet attain its desirable polishing characteristics through the use ofsubstitute polishing materials. One of these polishing materials hasbeen made of finely powdered 'silica because of its natural color andbecause it does not stain. Silica, however, proved inferior to rouge, asregards its polishing characteristics and the type of polish obtained onthe surface of glass articles. In addition to the above difficulties,silica has a decided disadvantage in that its use may involve a serioushealth hazard.

One of the prime, objects, therefore, of the present invention is tocompletely overcome the above difiiculties, as regards toxic andpigmenting conditions, through the provision of non-toxic andnon-pigmenting polishing materials or alternate materials possessing oneor more of the above characteristics and to provide fine grain materialadaptable to many other uses.

For ease in describing the present invention, we will consider theinvention as applied to polishing materials. In accordancewith thisinvention, hydrated aluminium silicate (clay), as mined or mined andpurified, is subjected to a controlled heat treatment, the limits oftemperature and time of which have been determined previously by test ortrial, for the purpose of producing a material suitable for use inpolishing, either directly or after it has been milled or ground to'break down aggregates, lumps or the like in said material, to reduce itso that no aggregates sufliciently large to interfere with the polishingaction remain.

quiring in some instances, purification preceding or subsequent to theheat treatment. To simplify matters, therefore, throughout the furtherdescription of the preferred form of the invention, thejbroad term claywill be used.

The clay material passes through several well defined stages during theheat treatment. Theoretically these seem to be as follows;

First, during the initial heating of from room temperature to about 450C., the mechanical and hygroscopic water is eliminated.

Secondly, the chemically combined water, if the chemical composition ofthe clay is A12O3.2SlO2.2H2O, the 2H2O is evolved or vaporized by anendothermic reaction (heat absorbing). Care should be exercised toseparate this water of hydration without too rapid elevation intemperature so as to avoid sintering of particles together by thepossible fluxing action of the water. Therefore, at the second stage,between 500 to 600 C. this 2H2O should be substantially eliminated.

Thirdly, the heating is continued to break up the structure of thealuminium silicate to reduce it to the desired condition. Practicaltemperatures will be discussed later. At this stage the clay is reducedto a practical polishing material with the exception that perhaps somelarge aggregates might be present. These, however, are easily brokendown through subsequent treatmerit, as by milling, rolling or the like.It is important, that the third stage of heating be not carried too faras the material will then not produce as good a polished surface.

broken down, tend to scratch the surface which is being polished by saidmaterial due to mechanical action. The limiting of the temperature towhich the heating is carried, in this third stage,

is important, as above set forth. We find that above 1350 C. the changeinto an undesirable structure begins to take place very rapidly so thatthejclay should not be heated above 1350 C. The temperature need not becarried as high as 1350 C. in order to effect the desirabletransformation, as this action begins to take place at about 400 C.Within the range of 400 C. to 1350 C., the desired transformation takesplace more rapidly and more completely as the temperature is elevated.

It has been found, through the use of samples of clay which have beenprepared and tested by the; standard tests which we use to evaluatepolishing compounds, that the quality of polish obtained can be verywell explained by the weight of glass which is removed from the testglass and by a general description of the appearance of the surface. Inthis test, a flat disc of glass is polished with the material under testunder standard carefully controlled conditions. The table which followssets forth some general results on a specific material, commerciallyin... as United Clay Mines Putnam .clay, a Florida kaolin.

Caicina- Tempera- Removal Surface tion tum rate quality "0. F.Milligrams 482 900 4. 2 Poor.

1M0 l6. 6 D0. 503 1100 30. 8 Fair. 648 1200 as. 4 Do. 704 1300 41. 0Good. 760 1400 44. 4 Do. 816 15m 45. 6 Do. 871 l 43. 2 D0. 020 1700 30.0 Fair. 081 1800 37. 2 Do. 1036 1900 36. 0 Do. 1093 2000 45. 4 Poor. 1N42M0 58. 6 Do. 1315 2400 57. 2 Do. 1427 2600 54. 0 Do. 1610 2760 53. 4Do.

It will be noted, by the chart set forth above, that as calcination isstopped at F. intervals between the 900 F. and 1500 F. the rate ofremoval and quality of the polished surface increases steadily to amaximum. It will be noted that from 900 to 1100 F. the surface qualityis poor and rate of removal is relatively low. From 1100 F. to 1300 F.,the rate of removal increases and the surface quality is better. From1300 F. to 1600 F. the removal rate is relatively high and the surfacequality good. The surface quality, however, between 1600 F. and 1-700 F.commences to fall off and the removal rate also diminishes. Thisreduction of removal rate and change of surface quality from good tofair continues to approximately 1900 F. whereupon the surface qualitythen decreases to a very poor state although the rate of removalincreases. This increased rate of removal is probably due to; thecrystalline structure which the material develops at such hightemperature. By comparison of these removal rates, with the removalrates of thebest polishing rouges, it is found that they are of the sameorder of magnitude. The polishing material, however, as produced by claytreated aslspecified above is non-toxic and non-pigmenting and is inthis manner more desirable than rouge. Other clays have given evenbetter results.

The duration of heating at the temperature chosen does not seem to be avery important factor beyond a reasonable time. Equivalent removal ratesand surface quality were obtained whether the clay was held at themaximum temperature of calcination for two hours or for several days. Ofcourse, the necessary length of time depends on how large a bulk ofmaterial is being heated and how easily the temperature gradient fromthe outside to the interior of the mass is smoothed out or equalized. Asevidence for this point of consideration, batches of Florida clay wereheld at 1500 F. (815 C.) for the times given, as illustrated in thetable below.

Time Rate of removal Surface quality Hours Milligrams 0. 5 Fair togood. 1. 2 51. 0 Good. 2 52. 0 Do. 4 58. 4 Do. 8 56. 8 Do. 24 57. 2 Fairto good If the heat is prolonged for too long a time the formation ofsome undesirable hard material seems to take place.

The material obtained at 1500' 1". (815 C.) is

very soft and fine-grained, but the particles do remain in friable lumpswhich-must be broken up by some means.

To effect this breaking up suitable ball-milling or the like my beemployed. The milling process may be carried on either wet or dry. It

has been found, however, that wet milling is more desirable fromthestandpoint of avoiding caking up with the result that a more rapidmilling action takes place. The material may be used in this conditionor may be subjected to a subsequent drying process. It is important tonote that although a wet milling is employed the clay does not reabsorbthe liquid used in the milling process and decreases its polishingability, that is, it does not have any tendency to return to its initialstate; A120:.2S1O2.2H2O.' Samples of said material have been retained inwater for many months without deteriorating its polishing ability. 1

The time of milling depends I upon the size and charging of themill. Itshould be continued at least long enough to reduce all of the materialto finer than 200 mesh, which is a standard accepted term used inscreening.

The following clays which have been found practical for use are setforth herein only by way of illustration: Georgia and Florida clays orother sedimentary clays which have been freed from mica, feldspar,quartz or other accompanying gritty minerals through geologicalprocesses; as

forexample, by nature's transportation through how of water or the like.Other clays may be used which have been freed by subsequent industrialprocessing from such accompanying minerals. It is to be understood,therefore, that the clays given here are only given byway ofillustration.

The temperature controls and treatments given herein are set forth forrendering the various materials usable as polishing ingredients and such'reatments may also apply for rendering the materials practical forother uses. In following out this treatment suitable temperature controlmust be obtained. For ease of description we have given the temperaturecontrols of a particular clay (Florida kaolin) but it is to beunderstood that anyone skilled in the art could apply these teachings toother clays or other materials.

In following the steps of this heat treatment and in order to arrest itat the optimum point any of the techniques familiar in ceramictechnology may be used. For the purposes set forth, the final test isalways how the material will polish glass, but for other purposes othermeans for determining the optimum temperature for arresting thecalcination may be desirable. We may mention changes in index ofrefraction, specific gravity, in the X-ray diffraction pattern, in thebulk weight, and the tendency to tellydrate. One of the most used andsimpler methods for following the course of calcination is by measuringthe differential rate of heating. In this method the clay, in a suitablecontainer, is placed 'in a furnace. A thermocouple is embedded in theclay or other material and the temperature changes measured incomparison to that of the furnace as the temperature of the furnace israised at a constant rate. This is diagrammatically illustrated in thefigure of the drawing by a chart showing the differences in.

temperature. The temperatures of a Florida kaolin and the furnace inwhich it was heated are recorded at different time intervals for the 3duration of the heating. Referring to the curve .A of the chart it maybe seen that the maximum freely exposed to the furnace atmosphere. Fromcurves of this type the desired maximum temperature of calcination canbe determined for any of the materials set forth above. The finding ofthis method should then be checked by actual service test and correctedaccording to the results of said test.

Although the invention has been described as for use in polishing glassarticles, materials .resulting from this invention may be used for manyother purposes such as a substitute for pumice to eliminate thescratching characteristics of pumice; for use in toothpaste; for use inpurifying oils and other liquids in a manner for which charcoal or likeis used; for use as filter means; for use in impregnating felts toproduce dust filters; for use as a solid absorbent either in granularform or by brioketing; for use as a catalyst or carrier for catalysts;and for many other purposes.

In general it, is desirable to obtain such a material that has nopigment so it will not stain, and also that is not toxic so it will notbe a health hazard.

The procedure is to treat, clay by heating it to a certain definitetemperature that has been proven by test or trial to be the optimum, andthen further treating it to remove impurities and scratchy particles.The consideration is to heat treat the material to a temperature thathas been proven by trial or test to produce the best polishing results.The proper temperature and exposure for any material under considerationis obtained empirically by test and trial for that particular material.

Poisons may be removed in some cases by further heating, and in somecases poisons may be removed by washing.

The controlling factor is whether or not the material so operated uponproves on test to be adaptable for the results required. The limits ofoperation are empirically determined as has been stated above.

From the foregoing description it will be seen that a simple, eflicientand economical means and methods have been provided for accomplishlngall of the objects and advantages of the invention.

Having described our invention, we claim:

1. A material for use as a polisher, a cleanser, a purifier, a catalystor a catalyst carrier or other uses comprising a fine grained,non-toxic, non-staining material resulting from the heat treatment of abatch of kaolinic clay for a time interval suflicient to heat theindividual particles of clay to a temperature ranging between 1000 to2100 F., with the temperature of the heat used in said treatmentaccording to the particular batch of clay, being of a given amountwithin said range so as to be below the temperature point at which itwill cause an appreciable portion ofsaidclaytosinterintohardlmnps.comparedwithrouge.

uses comprising a fine grained, non-toxic, nonment' of a batch ofkaolinic clay for. a time inof clay to a temperature ranging between1300 to 1600" F., with the temperature'of the heat 1 media saidtreatment according to the particua'ndlose its eifectivenecs as a glasspolisher as -2. A material for use as a polisher, a cleanser, apurifier, a catalyst or a catalyst carrier orother 5 with!!! 8811! me soas to be adjacent to but below the temperature point which will cause anstaining material resulting from the heat treat- 1 lar batch of clay,being of a given amount with 5 in said range so as to be below the temprature 1 pared with rouge. V

3. A material for use as a polisher, a cleanser, a purifier, a catalyst,or a catalyst carrier or other 1 usescomprising a fine grainednon-toxic, nonstaining material of a physical state that will polishglass without scratching resulting from the 5 heat treatment of a batchof kaolinic clay for a f time interval suflicient to heat said clay to agiven 1 temperature ranging from 1000 to 2100 F. depending upon theparticular type of clay used 1 for said batch with the temperature socontrolled according to the particular batch of clay as to be jsufiicient to develop a physical state of said indi- Mvidual particlesthat will polish glass with subf stantially the efficiency of rouge.

4. A material for use as a polisher, a cleanser,

1 uses comprising a fine'grained, non-toxic, nonstaining material of aphysical state that will 4 r a,aso,sas

the individual particles of clay to a temperature a in between 1000 to2100' It. with the temperatureusedin said treatmentaccordingtotheparticular batch of clay being of a given amountappreciable portion of said clay to sinter into hard lumps and lose itseffectiveness as a glass terval sufilcient to heat the individualparticles P 1 88 c mpared with rouse.

6.. The process of forming a material for use as a polisher, a cleanser,a purifier, a catalyst or catalyst carrier or other uses, comprisingforming a fine-grained non-toxic, non-staining material to a physicalstate that will polish glass without scratchingby heat treating abatchof kaolinic clay for a time interval sufilcient to heat the individualparticles of clay to a temperature ranging between 1000 to 2100' F.,with the temperature used in said treatment, according to the particularbatch of clay, beingjof a given amount within said range so as to beadjacent tobut below the temperature point which will cause .an,

appreciable portion of said clay to sinter into hard lumps which aredlflicult, by subsequent processing, to break down to the polishingcharacteristics desired, the said given temperature being originallyobtained by heat treatmentof said clay to different temperatures withinthe above range and by trial of the materials produced by said differenttemperatures, in polishing until a temperature is reached that trial ofthe material resulting therefrom in polishing a glass with said materialdemonstrates that said material will give a purifier, a catalyst or acatalyst carrier or other polish glass without scratching resulting fromthe 1000 to 2100 F., with the temperatureoftheheat I used in saidtreatment according to the particular batch of clay, being of a givenamount within 1 said range so as to be adjacent to but below the 1temperature point which will cause an appreciable portionv of said clayto sinter into hard 1 lumps which are diflicult, by subsequent process-1 ing, to break down to the polishing characteristics desired, the saidgiven temperature being originally obtained by heat treatment of saidclay to difierent temperatures within the above range 3 and by trial ofthe materials, produced by said diiferent temperatures, in polishinguntil a temperature is reached that trial of the material 1 resultingtherefrom in polishing a glass with said material demonstrates that saidmaterial will give the maximum non-scratching efliciency, surface 1qualit producing nature and a speed of operaj tion substantially equalto that of rouge.

5. The process of making a material for use as i a polisher, a cleanser,a purifier, a catalyst or a 1 catalyst carrier or other uses, comprisingform- 1 ing a fine grained non-toxic, non-staining material to aphysical state that'will polish glass tion substantially equal to thatof rouge.

7. A glass polishing material comprising a fine grained, non-toxic,non-staining material of a physical state that will polish glass withoutscratching, resulting from the heat treatment of a batch ofsubstantially pure kaolinic clay at a temperature and for a timeinterval sufficient to heat the individual particles of clay to atemperature of approximately 1500 F. to 1600 F., with the temperature ofthe heat treatment for said particular clay being sufficient to developa physical state of said individual particles that will polish glasswith substantially the efliciency of rouge, and below the temperature atwhich the material resulting therefrom will lose its e'flectiveness orefficiency as a glass polisher as compared with rouge.

8. A polishing material for glass, said material resulting from the heattreatment of a batch of hydrated aluminum silicate consistingessentially of the mineral kaolinite, for a time interval and at atemperature suflicient to heat the individual particles of said materialto a temperature between 1100 F. and 2100 F., the temperature used insaid treatment being below that at which the heat will cause anappreciable portion of said material to sinter and lose itseffectiveness as a

